diff --git a/cms/core/class/CodePressCMS.php b/cms/core/class/CodePressCMS.php
index 7ca4b7e..557be0e 100644
--- a/cms/core/class/CodePressCMS.php
+++ b/cms/core/class/CodePressCMS.php
@@ -579,9 +579,9 @@ class CodePressCMS {
         // Auto-link page titles to existing content pages (but not in H1 tags)
         $body = $this->autoLinkPageTitles($body, $cleanName);
         
-        // Convert relative internal links to clean URLs
+        // Convert relative internal links to clean URLs (skip already-prefixed URLs)
         $body = preg_replace('/href="\/blog\/([^"]+)"/', 'href="/' . $this->currentLanguage . '/blog/$1"', $body);
-        $body = preg_replace('/href="\/([^"]+)"/', 'href="/' . $this->currentLanguage . '/$1"', $body);
+        $body = preg_replace('/href="\/(?!nl\/|en\/|nl"|en")([^"]+)"/', 'href="/' . $this->currentLanguage . '/$1"', $body);
         
         return [
             'title' => $title ?: $cleanName ?: 'Untitled',